This invention relates generally to instruments for the measurement of elevated temperatures in gas filled chambers and specifically for the measurement of the elevated temperatures of combustion chambers such as in the gasification of coal in a partial oxidation process carried out within a reactor vessel shell that is lined internally with successive courses of refractory materials.
In this process it is well known that high temperatures result in the production of liquid slag which interacts with the refractories in a manner destructive to the refractories. As a result, the hot face of the innermost refractory is gradually eroded away during the operation of the gasification process, and as the refractory is worn away thermocouples used to measure the temperature of the process are exposed and are themselves destroyed by erosion. Consequently it has become usual to protect the thermocouples with a casing of refractory material, and also it has become advantageous to use a plurality of thermocouples in a bundle, each one being recessed farther than another within the hot face of the innermost refractory. Then as one thermocouple is destroyed by the high temperature slag, another one backing it up takes its place. If the back-up thermocouple is destroyed in turn, another one behind it comes into play. The result of these steps to protect the temperature measuring devices is that the thermocouple bundle plus its refractory casing becomes quite heavy, and since, in addition, the thermocouples need to be long enough to extend through the thick refractory courses the weight of the bundle and casing is concentrated at a substantial distance away from the point of support, with the result that it is difficult to provide adequate thermocouple support.
At the same time another problem arises as the high temperature innermost refractory course of the reaction chamber lining expands upwardly more than the lower temperature shell of the reactor vessel. The result is that the innermost refractory course tends to come in contact with the thermocouple casing, which is attached to the reactor vessel shell. In extreme cases such contact can have a destructive effect on the thermocouple bundle and casing.
This invention provides a novel means of supporting the long heavy thermocouple bundle and casing and at the same time provides for expansion of the inner hot face refractory material without its coming in contact with the thermocouple casing. An advantageous aspect of the present invention design is that construction is simplified and use is made of readily available components for which no special machining is required. Installation and servicing are simplified as the design uses standard techniques and components. Also a simple design is provided for the transition from the individual elements of the thermocouple bundle to a standard wire sealing transducer gland. Whereas conventional means of supporting an elongated thermocouple bundle, such as is used to extend through the thick refractory walls of a combustion chamber, involves a cantilever design in which the weight of the heavy thermocouple bundle is supported by a long lever arm exerting a substantial torque at the point of attachment to the reactor vessel shell, this invention provides an improved means of supporting the weight directly at a point near its center of gravity without use of a cantilever design and in a manner that makes use of readily available standard components. At the same time the improved means of this invention avoids the problem of damaging contact between the expanding refractory and the thermocouple casing.